Excel 2007 : How to attain matching

hi
Gurus

i have a column with dynamic values, they may change depending on the user input

say from a1 to a25
each cell is dynamic subject to user input (monthname)


i have two columns with values


column i column j
may a
june b
july c
augusta d
september e
october f
november g
december h
january i
february j



now based on the user input (month)

i would like to get the values in column j


please advice

thanks